The present invention relates to the game of golf and more particularly to an improved design concept for a set of golf clubs.
The game of golf is probably at the height of its popularity, and designers of golf clubs are striving to attain not only better quality equipment, but also equipment that will facilitate the play of the game. As is generally known, sets of golf clubs comprise two types of clubs, basically woods and irons. The present invention relates to the design of the iron type club.
Present day iron club designs fall into two general categories; first, the traditional type of design wherein the iron is forged and has a generally continuous back portion on the club blade; the second type of iron design is referred to as the "cavity back" design wherein the back portion of the club blade includes a substantial depression or cavity which has the effect of providing perimeter weighting for the club head. In contrast with the more conventional solid back iron, perimeter weighting provides a larger "sweet spot" or hitting area. That is to say, the cavity back type of club head is rather forgiving and is designed so that the ball does not have to be struck precisely in the center of mass of the club to attain acceptable results.
In order for the reader to appreciate fully the concept of the present invention, some basic principles of golf club design and more specifically the design of iron type golf clubs are reviewed hereinafter. The present disclosure is, however, directed to one skilled in the art of the design of golf clubs and as such certain well known terms of art will be employed without detailed explanation. In this regard, it will be readily appreciated that a set of irons comprises a plurality of clubs commencing with the clubs of lesser loft, as for example the two-iron and three-iron and progressing toward the clubs of greater loft, such as the eight-iron, nine-iron and pitching wedge. The length of the club shaft employed with each iron varies with the loft of the club, such that the lower numbered, less lofted irons have longer shafts than the higher numbered, more lofted irons. One of the desired features of golf club designs is to attain a relatively uniform swing weight from club-to-club throughout the set of irons. In order to attain the desired uniformity in swing weight, it is necessary that the club heads vary in their weight and mass, in relation to the varying lengths of shaft employed. That is to say, with the longer shaft on a two-iron, the two-iron club head will be of a lesser mass or weight than the club head of a nine-iron, which utilizes a shaft of shorter length. In this regard, attention is invited to the table which can be found in the detailed description of the invention and the various dimensional features noted therein.
With the above discussion in mind, attention is now directed to some of the problems encountered with present day iron club designs, both those of the traditional style and those of the cavity back style. With both types of prior art designs, the length of the hosel on the club head is relatively constant from club-to-club in the set. The hosel is the tubular portion of the club head which has the shaft affixed thereto. With the hosel length constant from club-to-club, the location of the center of mass will vary with the respective clubs. More specifically, with a two-iron and the lesser mass of the club head, the center of mass will be closer to the hosel, than will be the center of mass for a more lofted iron, such as a nine-iron. Thus, with present day designs, as we progress through a set of clubs starting with the lower lofted irons, the location of the center of mass moves outwardly along the club head blade away from the hosel and toward the toe of the blade. This variance in the location of the center of mass or the "sweet spot" is an undesirable feature that can adversely effect play. This phenomenon or disadvantage is present not only with the traditional forged type irons, but also with the cavity back irons. As will be discussed in further detail hereinafter, the employment of a cavity back type of iron presents even greater problems when a constant hosel length is used.
With a cavity back type of iron, the present day designs utilize a relatively uniform cavity size or dimension from club-to-club. That is to say, the approximate volume of the cavity for a two-iron will be about the same as that for a nine-iron or pitching wedge. Keeping in mind the fact that the weight of the club head increases as we progress through the clubs of the set, with the cavity volume remaining approximately constant, the increase mass of the club can only be accommodated at two locations, that is the increased weight can be placed either on the sole of the club, or proximate the toe of the club, or portion allocated to both locations. Consequently, there is provided a club head either with a relatively thick sole and/or an oversized, weighted toe portion. Both of these are undesirable features in higher lofted iron clubs. The placement of increased or excess weight in the sole of the clubs causes the ball to fly higher than desired. With the elevated loft of the club face there is no need for this increased sole weighting. The addition of weight at the toe location of the higher lofted club is also undesirable, as this will cause the club face to close during the golf swing. With the center of mass disposed relatively outward toward the toe, the closing of the club face can produce errant shots, or at the very least, shots of lesser accuracy than is demanded by the more skilled players of the game of golf. It is for this reason, that the cavity backed or forgiving type of iron is rarely employed by a professional or tour player.
Further, with respect to the lower numbered less lofted irons of the cavity backed design, the employment of a substantially uniform cavity generally results in a compromise, with the volume of the cavity being determined for the intermediate lofted clubs, such as the five-iron or six-iron. Thus, with the lower lofted clubs in the two and three-iron range there is not attained a sufficient degree of sole and toe weighting that is beneficial with the lower lofted clubs. With the lower lofted clubs it is preferred to have a considerable amount of the club head weight or mass proximate the sole and toe areas to prevent the blade from opening during striking of the ball, and also to place a substantial amount of mass below the ball to assist in attaining the desired angle of flight. As anyone who has played the game of golf can attest, it is often difficult to get the golf ball airborne with the lower lofted clubs, such as a one-iron, two-iron or three-iron.
The golf club design of the present invention overcomes the above-discussed disadvantages by employing a number of features which can be utilized independently or in combination to provide an improved, more playable iron type club. Initially, one of the important features of the present invention is the employment of an iron club head design for the various clubs of the set wherein the hosel portion on the lower lofted irons are of a shorter length, and therefore less mass or weight than are the hosel portions on the higher lofted irons. Thus, as the club head weight increases from the lower lofted to the higher lofted irons, the weight of the hosel portion also increases which permits the center of mass or "sweet spot" to be maintained at a relatively constant location in relation to the blade portion of the club head, and the planar face of said blade portion. Secondly, the present invention envisions employment of a cavity back type of club to attain the benefits of perimeter weighting, which as it will be recalled is the attainment of an enlarged "sweet spot" or hitting area and a more forgiving type club. That is to say, even if the ball is struck slightly off center relatively acceptable results can be attained. In this regard, the size or volume of the cavity in terms of the mass of material that is effectively removed from the blade due to the presence of a cavity is varied from club-to-club, with the lower lofted irons having a larger cavity than that employed with the higher lofted irons.
The advantages attained with the varying of the cavity size are significant and several in number. Initially, it must be kept in mind that in designing a set of iron clubs the approximate weight of the various club heads is first determined. Thus, given a particular club head weight for a lower lofted iron, the employment of a larger cavity permits placement of a predetermined portion of the club head mass or weight proximate the sole and toe sections of the club head. The increase mass in the sole section is desirable in that it facilitates getting the ball airborne and results in attainment of the desired trajectory for the shot. The placement of weight in the toe of the club is beneficial in that this weight and moment generated during the swing will tend to offset the torque generated upon striking the ball, and prevent the blade from opening during the dynamic portion of the golf swing, viz., that portion of the stroke when the ball is struck and the energy from the club head is transmitted to the golf ball. With the higher lofted irons, a smaller cavity is employed, which has the effect of enabling the designer to provide a smaller overall club head. In this regard, if the cavity size were the same for the two-iron as for the nine-iron, considerably more weight would have to be provided proximate the sole and toe portion of the nine-iron as the club head weight is greater. Since only so much weight can be added to the sole portion of the club before the size thereof becomes unsightly and a hinderance, the end result is that most of the excess weight is placed in the toe portion resulting in extremely large, elevated toe segment and a somewhat oversized or larger club head than is desired. With the present invention, the varying of the cavity size enables the provision of a lower toe portion and a smaller overall club head configuration. Further, since less of the club head weight is allocated to the sole and toe portions, the club design of the present invention is not subject to the disadvantages discussed above with the prior art cavity back designs. That is to say, the smaller cavity for the short irons allows a more even distribution of weight across the entire back of the blade, thus enabling the size of the club head to be smaller and avoiding excessive toe and sole weighting.
The present invention provides still an additional feature which facilitates fabrication of the iron type clubs. More specifically, the rear portion of the club head, that is the portions in which the cavity is formed includes a rim or ridge extending about the entire periphery of the club head, which permits the club head weight to be adjusted after the club head has been finished. In practice, the club heads are forged and finished to an approximate or target weight by a foundry. In the assembly of the club head to the shaft a desired swing weight is sought to be attained. Quite often, it is necessary to remove or add a slight amount of weight from the club head in order to achieve the desired swing weight. With the present invention, the rim about the periphery of the rear portion of the club head can be ground to permit attainment of the desired swing weight, without adversely effecting the finish of the club head disposed inwardly of the rim portion.